Components of ongoing EEG with high correlation point to emotionally-laden attention — a possible marker of engagement?

Recent evidence from functional magnetic resonance imaging suggests that cortical hemo-
dynamic responses coincide in different subjects experiencing a common naturalistic
stimulus. Here we utilize neural responses in the electroencephalogram (EEG) evoked by
multiple presentations of short film clips to index brain states marked by high levels of corre-
lation within and across subjects.We formulate a novel signal decomposition method which
extracts maximally correlated signal components from multiple EEG records.The resulting
components capture correlations down to a one-second time resolution, thus revealing
that peak correlations of neural activity across viewings can occur in remarkable corre-
spondence with arousing moments of the film. Moreover, a significant reduction in neural
correlation occurs upon a second viewing of the film or when the narrative is disrupted
by presenting its scenes scrambled in time. We also probe oscillatory brain activity during
periods of heightened correlation, and observe during such times a significant increase in
the theta band for a frontal component and reductions in the alpha and beta frequency
bands for parietal and occipital components. Low-resolution EEG tomography of these
components suggests that the correlated neural activity is consistent with sources in the
cingulate and orbitofrontal cortices. Put together, these results suggest that the observed
synchrony reflects attention- and emotion-modulated cortical processing which may be
decoded with high temporal resolution by extracting maximally correlated components of
neural activity.